ENDOCRINE DISCRUPTORS


        Endocrine disruptors have come into the limelight recently with the publication of "Our Stolen Future -- Are We Threatening Our Fertility, Intelligence and Survival?" ( T. Colborn, J.P. Myers and D. Dumanoski, 1996). It is feared these synthetic compounds (also known as environmental hormone disruptors or xenoestrogens) interfere with the hormonally controlled processes of the body such as growth and development, sexual differentiation and behavior, and reproductive functions. Existing information is not able to determine if the fears are well founded since the levels of synthetic endocrine disruptors in the environment are considerably lower than regular intake of naturally occurring ones.

        What Kinds of Chemicals May be Endocrine Disruptors? A variety of synthetic compounds act as endocrine disruptors. These include some chlorinated organic compounds (particularly some pesticides such as DDT), some plasticizers and breakdown products of certain plastics, and some pharmaceuticals (e.g. diethylstilbestrol). Some varieties of vegetables contain naturally occurring phytoestrogens which have similar properties to endocrine disruptors.

        What Health Effects May Endocrine Disruptors Have? Hormones produced naturally by our bodies control important functions which include growth, development, sexual behavior and differentiation, and reproduction (e.g. estrogens and androgens). Some synthetic chemicals are able to repress or stimulate the action of these hormones in a variety of ways, therefore, it is feared that excessive exposure to such chemicals may have undesirable biological effects. It is unclear whether the small concentrations of xenoestrogens present in the environment are capable of having any significant effect. The book, "Our Stolen Future", however, expresses the hypothesis that endocrine disruptors contributed to the reported increases in recent years of abnormal or incomplete genital formation; testicular, prostate and breast cancer; reduced sperm count in men; and reduced intelligence in children.

        How May I be Exposed to Endocrine Disruptors? The chemicals of concern can be found in trace quantities in the air, water and food supply. Some high local contamination (such as a pesticide spill) may occur in certain areas.

        Are Endocrine Disruptors Likely to Affect Myself or My Children's Health? The levels of synthetic chemicals present in the environment are typically much less than our dietary intake of naturally occurring phytoestrogens found in certain vegetables (e.g. soybeans, corn, and wheat). Woman can receive much higher doses of estrogen through birth control pills or post-menopausal hormone replacement therapy. Modern birth control pills have not been related to an elevated risk of cancer. Further research is required to determine if the low levels of xenoestrogens typically experienced are detrimental.

        What Is the Current Status of Our Understanding? Currently, our scientific understanding of endocrine disruptors is poor. As a Harvard University publication puts it (Rhomberg, 1996):

The wide span of opinion on [endocrine disruptors] is typical of the early stages of an emerging scientific question, when possibilities of great concern are raised, but existing information (and, perhaps more importantly, scientific consensus about the meaning of that information ) is insufficient to resolve whether or not emerging fears are well founded. If the environment is indeed accumulating compounds that can have widespread and serious effects on the health, development and fertility of wildlife and humans, then we face a great problem; such compounds will be difficult to control and even more difficult to remove from the environment. On the other hand, if low exposure levels pose little real risk, then a crash program of xenoestrogen control and cleanup will divert precious resources from other pressing environmental problems.




Source: http://www.ci.sf.ca.us/puc/wqfs/tocsec4.htm